Gas turbine rotor arrangement



I 1953 B. o. BUCKLAND ETAL 2,655,307

GAS TURBINE ROTOR ARRANGEMENT Original Filed June 11. 1947 2Sheets-Sheet 1 Inventors: Bruce QBuckland,

Chester SRice,

Their Attorney.

Oct. 13, 1953 B. o. BUCKLAND ETAL 2,655,307

GAS TURBINE ROTOR ARRANGEMENT 2 Sheets-Sheet 2 Original Filed June 11,1947 w a N g 3-? N I g m 1* no Q a es Q a; m Inventors: 1 a O BruceQBuckland, fig Chester SRice,

N y w Then" Attorney.

Patented Oct. 13, 1953 GAS TURBINE ROTOR ARRANGEMENT Bruce 0. Bucklandand Chester S. Rice, Schenectady, N. Y., assignors to General ElectricCompany, a corporation of New York Original application June 11, 1947,Serial No. 754,002. Divided and this application February 1, 1951,Serial No. 208,961

6 Claims. (01. 230-116) This invention relates to gas turbinepowerplants, particularly to a novel rotor arrangement for such apowerplant including an axial flow compressor rotor of substantial axiallength supported by a journal bearing at either end thereof, amulti-stage turbine rotor of substantial axial length supported by ajournal hearing at either end thereof, a single thrust bearing forlocating the rotor assembly in an axial direction, a special thrust linkfor locating the two rotor portions axially relative to each other, andspecial means readily adjustable from the exterior end of the powerplantfor shifting one of the rotors axially relative to the other so as tomaintain the clearances between rotor and easing at a desired value.

This is a division of an application Serial No. 754,002, filed June 11,1947 in the names of Alan Howard, Chester S. Rice, and Bruce 0.Buckland, and assigned to the same assignee as the present application.

Generally, the object of the invention is to provide an improvedcomposite rotor arrangement for a compact integral gas turbinepowerplant especially adapted for mobile applications in marine craftand locomotives. In such applications it is particularly desirable thatthe gas turbine powerplant be a self-contained unit so as to facilitatethe mounting of the plant on the frame of the ship or locomotive,without the necessity for complicated high temperature piping andtroublesome expansion joints. The powerplant to which this inventionrelates has a rigid frame-work capable of maintaining accurate bearingalignment and in turn being adapted to be supported at three points soas to be un'aifected by deflections in the frame of the craft in whichthe powerplant is mounted. The special frame-work of this powerplant isdescribed more completely in United States Patent 2,591,399 issued March31, 1953 in the names of Bruce 0. Buckland and Alan Howard. Thethreepoint support for the powerplant is described in United StatesPatent 2,632,997 issued March 31, 1953 in the names of Alan Howard andBruce 0. Buckland, both assigned to the same assignee as the presentapplication.

In a powerplant of the type described, having comparatively longcylindrical combustors aligned between the discharge end of a multistageaxial flow compressor and the inlet of a multi-stage turbine, it isinevitable that the overall length of the powerplant will become sogreat that at least three, and usually four or more, journal hearingswill be required to support the compressor and turbine rotors. The mostobvious bearing arrangement would be to have two bearings for eachrotor, with one thrust bearing associated with each rotor for locating gthe respective stator members.

2 it in an axial direction and absorbing the thrus loads arising fromtheoperation of the compressor and turbine respectively. A specific objectof the present invention is to provide a gas turbine rotor assembly soarranged that only one thrust bearing is required, with special meansfor locating both rotors from this single thrust bearing.

In a gas turbine powerplant it is important that the turbine andcompressor rotors be located in an axial direction very accuratelyrelative to This is particularly true of the turbine rotor, since axialpositioning of the bucket-wheels relative to the turbine nozzles has aninfluence on turbine efiiciency; and at the same time it is particularlydiflicult to maintain the required turbine rotor clearances by reason ofthe high temperatures in that part' of the powerplant. Accordingly, itis .a still further object of the invention to provide novel means foradjusting the turbine rotor axially relative to the compressor rotor,this adjustment being effected from the exterior end of the powerplantwithout substantial disassembly thereof.

Other objects and advantages will become apparent from the followingdescription, taken in connection with the accompanying drawings, inwhich Fig. 1 is a view partly in section of the compressor rotor, Fig. 2is a sectional view showing the turbine rotor and the frame and bearingstructure therefor, Fig. 3 is a detailed sectional view of the thrustlink arrangement connecting the compressor and turbine rotors, Fig. 4 isa transverse view partly in section of the thrust bearing assembly, andFig. 5 is a detail of the arrangement for adjusting the turbine rotoraxially.

Generally, the invention is practiced by providing the compressor andturbine with journal or other suitable radial type bearings at therespective ends of each rotor, with a single thrust hearing associatedwith the compressor rotor at the end adjacent the turbine rotor, athrust link assembly for transmitting'torque between the turbine rotorand the compressor rotor and for pcsitioning the turbine rotor axiallywith respect to the compressor, and providing special means at theexterior end of the turbine rotor for effecting axial adjustmentthereof.

Referring now more particularly to Fig. 1, the compressor assemblyincludes an inlet casing, shown partly at I, having an air inlet openingcommunicating with the annular compressor inlet passage 3, the innerwall of which is formed bya substantially cylindrical wall 4, which iscast integral with the support ring 5 carrying a first journal bearing6. This journal bearing may be of any conventional babbitt-lined orother suitable type, and may be secured by suitable threaded fasteningsI to the casing portion 3. Extending across the compressor inlet passage3 are a" plurality of circumferentially spaced vanes 8 formed integralwith the outer wall of casing I and with the inner wall is, which latteris a continuation of the frame cylinder 4 and forms the inner boundaryof the compressor inlet passage. Cast integral with the top'outer wallof the inlet casing I is a boss 9 to'which may be secured a lifting eye,shown in dotted lines at 9a for handling the compressor or the completepowerplant.

The casing of the axial flow compressor comprises two sections l0, II,each section being divided into two halves along a longitudinalhorizontal plane and secured together by suitable threaded fastenings(not shown). The left-hand end of the casing section I3 is Provided witha circumferential flange Illa bolted to a cooperating flange In on thecompressor inlet casing I. The right-hand end of easing section It isprovided with a circumferential flange IIlb bolted to a cooperatingflange Ila on casing section I I. The right-hand end of section II has aflange Ilb bolted to the main radially extending frame flange I2, whichis welded to, or formed integral with, an intermediate frame casingmember, a

portion of which is shown at I 3 and illustrated more completely in Fig.2.

By reason of the fact that the divided casings II), II are flrmly boltedto the respectivecontinuous integral flanges la, I2, the inlet and exitends of the divided compressor casing are caused to preserve their truecircular shape regardless of temperature changes which may occur duringthe operation of the machine. As may be seen ing l3 serves a number ofpurposes.

in Fig. 1, the intermediate compressor stator -ll extending entirelyaround the compressor. As will be apparent from the drawing, the boltsI5 pass through the flanges IOb, Ila and through the solid ring I4. Thisarrangement insures that the mid-portion of the compressor stator willalso be caused to maintain its true circular shape regardless of thermalor stress distortions during operation. Thus the comparatively longaxial flow compressor casing is divided into sections which are easy tofabricate and assemble to form a very rigid integral'frame for thecompressor. This is particularly important, since when mounted in alocomotive or marine installation it is intended to support the plant bythree fittings with the compressor casing in overhung relation to themain support members, which means that the divided compressor casingstructure must support the comparatively heavy compressor inlet casing Iand certain powerplant accessories fastened thereto (not shown) Theabove-described compressor stator structure is described more completelyin the copending application Serial No. 754,002, flled June 11, 1947, ofwhich the present application is a division. It may be noted, however,that the compressor stator sections I II, I I are provided with a totalof fifteen circumferential rows of stationary compressor blades I6,which may be secured in circumferential grooves in the stator sectionsby means of suitable dove-tail portions formed on the blade bases. Atits discharge end, stator section II is provided with threecircumferential rows of turning vanes I'I;which are arranged to divertthe compressor discharge air into a uniform axially directed flow.

Referring now to Fig. 2, the intermediate cas- An inner annular wall I8cooperates with the outer wall to form the annular compressor dischargepassage ls. across which extend six radial circumferentially spacedstruts 20. The walls I3, 13 form a diffusing transition sectioncommunicatin with a plurality of circumferentially spaced combustors,one of which is shown partly in elevation at 2|. Although there may beany suitable number, in this powerplant there are six combustors spacedcircumferentially around the axis of the plant. The construction ofthese is not necessary to an understanding of the present invention,being disclosed more fully in the United States Patent 2,547,619 ofBruce 0. Buckland, Serial No. 62,333, filed November 27, 1948 andassigned to the same assignee as the present application.

Cast integral with, or fabricated separately and welded into, the casingI3 is a substantially cylindrical but somewhat tapering frame member 22.This framemember has a radially projecting portion 23 secured to theinner casing wall I8 by a weld 24. With this arrangement the flow ofheat by conduction from the combustors to the frame member- 22 and thebearings carried therein is reduced to a minimum. At one end, framemember 22 serves to support a second Journal bearing 25, also a thrustbearing assembly 26, the details of which will be more particularlydescribed hereinafter in connection with Figs. 3 and 4.

At its right-hand end, frame member 22 is secured to another cylindricalframe member 21, at the other end of which is supported a third Journalbearing 28. Welded to the cylindrical frame member 21, in theneighborhood of the journal bearing 28 is a radially extending annularplate member 29 which has a circumferential row of'openings around eachof which is welded one end of a short cylinder member having at theother end a flange adapted to support the turbine end of the outercombustor casing. To the outer circumference of the plate 29 is welded acylinder 30 which entirely surrounds the transition end of thecombustion system. At its other end, cylinder 30 is welded to acontinuous ring 3|, to which is secured a main frame ring 32 by aplurality of threaded fastenings 33, in a manner which will be apparentfrom Fig. 2.

While the transverse plate 29 and axially extending cylinder 30 help tosupport the frame ring 3| from the inner frame cylinder 21, a principalportion of the support between these members is provided by a pluralityof circumferentially spaced diagonally extending ribs or braces 34,there being one such brace between each pair of adjacent combustors. Atits left-hand radially inner end, each strut is welded to the lefthandend of the frame cylinder 21, in a manner which will be apparent fromFig. 2. The intermediate portion of each strut is provided with aninwardly extending portion 34a welded to the radial plate 29. At itsouter end, the strut has an axially extending portion 34b welded to theouter surface of frame cylinder 30, and to the adjacent face of theframe ring 3|. Thus it will be apparent that members 34, 29, 30, and 3|provide an extremely rigid frame for supporting the main frame ring 32in fixed relation to the inner cylindrical frame member 31.

Secured to the main frame ring 32 by the bolts bolted together at ahorizontal plane.

.- s 33 is aninte'rstage turbine casing indicated generally' at 35 inFig. 2. This casing is formed in two halves, divided along a verticalplane through the axis of the turbine and secured togather by aplurality of threaded fastenings 36. At its downstream side, interstagecasing 65 is provided with a second radially extending flange secured bybolts 3'I-to a second integral main frame ring 38. Welded to theexterior face of ring 38 adjacent the inner periphery thereof is anexhaust casing fabricated of comparatively thin flexible sheetsincluding a somewhat conical external wall 39, a cylindrical inner wall40 and a discharge scroll 4| with a flanged outlet opening 42.

Projecting diagonally across the annular exhaust passage defined bywalls 39, 49 are a plurality of circumferentially spaced radially andaxially extending struts or ribs 43. It is convenient to use six ofthese struts, the same number as there are of the struts 34. At theradially outer end, each strut 43 is secured, as by bolting or welding,to the ring 38. Each of these struts projects through an opening in theouter exhaust casing wall 39 and through a second opening in theinnerexhaust casing wall 40. Surrounding each strut in spaced relationthereto is a cooling air shroud 44 which projects through the respectiveopenings in the exhaust casing walls 39, 40 and is welded to theperipheries thereof. These shrouds 44 form acooling air path surroundingeach strut 43 and serve to support the inner exhaust casing wall 40 fromthe outer casing wall 39. A plurality of guide vanes 45 are welded tothe air shrouds 44 and serve to direct the turbine exhaust fluidsmoothly outward into the exhaust scroll 4|.

At their radially inner ends, the struts 43 are welded to an integralconical frame member 46. At its exterior end, this conical casing isprovided with a heavy flange 41 to which is secured the housing 48 ofthe exhaust end journal bearing 49. The bearing housing 46 is forconvenience divided into two halves along a horizontal plane and securedtogether by threaded fasten- N members are designed to provide adequaterisidity so th t no external frame or foundation need be relied upon tomaintain the bearing alignment.

7 It will, of course, be appreciated by those skilled in the art thatthe problem of maintaining bearing alignment lnsuch a powerplantis'quite seri- .-ous where the axial length of the machine is so turbinerotor, a main coupling assembly for seing 50. The lower half of thebearing housing is provided with a projecting boss 5| which forms asocket for receiving a ball member 52 secured to an end support pedestal53. It will be apparent that the ball and socket arrangement 5|, 52, 53provides one support point for the powerplant which is fixed in allthree dimensions. The end of bearing housing 48 is closed by a capmember 54, which may also be formed in two halves Also secured to theend ring 41 of the frame member 46 is a labyrinth casing 55 providedwith seal members for preventing the flow of oil vapors 'from bearing 49to the left into the cooling air passages described hereinafter.

In addition to the universal ball support 5|, 52, 53, the powerplant iscarried at two other points in'a manner which need not be described morefully here, since it is covered in the abovementioned Patent 2,632,997of Alan Howard and Bruce 0. Buckland.

It will be apparent from the above description that the powerplant has"a complete integral frame-work consisting of the compressor. casing I,Ni, ii, the intermediate casing member l3, the axially extending framecylinder 21, the radially extending ribs 34, main frame rings 32, 36with the interstage casing 35 between, the radially and axiallyextending ribs 43, the conical casing memcuring the turbine rotor andcompressor rotor in driving relation, coupling means for connecting theexhaust end of the turbine rotor to a load output device, first andsecond journal bearings supporting the compressor rotor, third andfourth journal bearings supporting the turbine rotor, a thrust bearingassembly located intermediate the second journal bearing and the maincoupling assembly andlvarious bearing seals and rotor coolingarrangements.

The axial flow compressor, shown in partial section in Fig. 1, issomewhat of a hybrid" between the well-known drum type and the equallywell-known disc type" of turbo-machine rotor. Like the drum type, it hasno central shaft extending entirely through the rotor, yet it is likethe disc type in that it is built of separately fabricated disc members,each carrying-a circumferential row of moving blades. As will beapparent from Fig. l, the. discs are maintained in coaxial relation byan interfitting rabbeted hub portion and are held together by aplurality of longitudinal through-bolts. The construction of this rotorneed not be described further here, since it is covered in more detailin the application of Alan Howard and Chester S. Rice, Serial No.79,766, filed March 5, 1949, now abandoned and opened to publicinspection in accordance withthe Commissioner's notice of January 25,1949. It is to be noted, however, that, at either end, the compressorrotor has a disc member with an axially extending portion defining asupporting journal. At the'compressor inlet end, the end disc member 56has a journal bearing portion 51 supported in inlet end bearing 6. Thedischarge end disc member 58 similarly has a journal portion 59supported in the second journal bearing 25 (see Fig. 2).

The complex bearing and coupling assembly housed within the intermediatecasing member 22 may be better seen in the enlarged detail view of 3.The casing member 22 supports an inner bearing casing 60, which is notan integral casting but is formed in two halves split on a' horizontalplane and secured together by bolts 6|. This divided casing provides thesupporting means for the labyrinth seal 62 and the journal bearing 25,in a manner which will be apparent from Fig. 3.

The bearing casing 60 is supported coaxially in the frame member 22 bymeans of three or more longitudinal key members, one of which is shownat 63, Fig. 3, and may be seen partly in elevation in Fig. 4, which viewis taken on the irregular plane 4-4 in Fig. 3. The key 63 is seated in alongitudinal groove 64 in the outer circumference of casing 60, and maybe secured by a machine screw 65. Key 53 also projects radially-outwardand into a cooperating groove 66 in casing 22. As may be seen in Fig. 4,the parallel side surfaces ber 46 and the bearing housing 48, 54. Theseof key 63 snugly engage the cooperating surfaces of groove 33. withthree or more circumferentially spaced keys, as shown at "a, lib in Fig.4, the inner bearing casing It will be supported ex-' actly coaxial withthe frame cylinder 22, regardless of anydifferentialthermal expansionbetween frame member 22 and bearing casing 30. Furthermore, with thesekey members forming the support for the bearing casing 82, the flow pathfor the transmission of heat by conduction from'the combustion systemfrom the bearings is made to have very high resistance. This is, ofcourse, desirable, in that the bearings and the alignment thereof willnot be adversely affected by heat from the combustion system.

Air for pressurizing the labyrinth seal member 82 is supplied through asuccession of drilled passages 81 in casing 80. Aligned with theexterior end of passage 61 is a hole 68 extending radially through thekey 63. A cooperating passage I! is formed in the casing 22 and suppliesair under pressure to the passage '1. This pressurlzing air may bederived from the compressor by a suitable conduit (not shown). In orderto seal the space between key 63 and recess M at the place where thispressurizing air enters .the hole 68, an annular packing washer isprovided. This washer is slidably seated in the recess is in key 63 andis biased radially outward into contact with the bottom surface ofgroove 66 by means of a coil spring H seated in recess 88, as shown inFig. 3. Since the bearing casing 60 is split, while the frame member 22is an integral casting, it is necessary in assembly to bolt the twohalves of casing 30 together, assemble the keys 63, 63a, i322, etc. intheir respective keyways, and then slide the whole assembly axially intoplace in the frame member 22. During this process the spring-biasedwasher I0 may be depressed so as to be flush with the outer surface ofkey 83. The casing 22 with its keys is then slid axially into the framemember 22, whereupon spring ll biases the packing washer HI radiallyoutward to perform the sealing function intended.

The inner bearing casing 60 also serves to support the thrust bearingassembly indicated generally at 26. The rotor assembly is positionedaxially, and the axial thrust loads are taken by, a thrust flange 12formed integral with an intermediate portion of the rotor end member 58.Cooperating with the opposite faces of thrust flange 12 arebabbitt-lined thrust bearing members 13,14. These members are notcontinuous rings but are divided along a horizontal plane through theaxis of the rotor, as may be seen in Fig. 4. Each of the members 13, I4is provided with a seal in the form of a segmental ring 15, 15a locatedin an annular groove with close clearances between the ring and thesides of the groove but appreciable radial clearance between ring andgroove. The inner periphery of rings 15, 15a engar 1 shaft 59 with a fitwhich permits free sliding but with a, clearance sufficiently small .tosubstantially prevent oil leakage therethrough. The thrust bearingmembers 13, 14 form a rabbet flt with an intermediate spacer member 16.Members 13, H and the spacer 16 are held together by a circumferentialrow of bolts H, as may be seen in Figs. 3 and 4.

While the thrust members 13, II are divided along a horizontal plane, asshown in Fig. 4, the intermediate spacer ring 16 is divided intosegments' along a vertical plane. Thus when members ll, 14, 16 areclamped together by the bolts 11, they form an integral assemblysurrounding the shaft portion ll.

To provide the degree of flexibility required of the thrust bearing whenthe powerplant is used for locomotive application or in other placeswhere it must be mounted on a bed of appreciable flexibility, the thrustbearing members are carried by a gimbal mount which provides freelyself-aligning support. This gimbal support includes the followingmembers. Formed intesrai with the intermediate spacer ring II are a pairof diammetrically opposite gimbal trunnions, one of which is shown indotted lines at 18 in Fig. .4. These trunnions are pivotally supportedin side frame members ll, one of which is also shown in Fig. 4. The sideframe member 19 is secured, as by suitable threaded fastenings 82, tothe ends of arcuate ring members SI, 32. It will be apparent that themembers 19, 8|, 82 form the gimbal frame. At diammetrically oppositeintermediate portions, the segments II, a: are provided with trunnions83, 84. These are pivotally supported in bosses 85, 8| in a manner whichwillbe apparentfrom Figs. 3 and 4.

As will be apparent from the drawings and the above description of thebearing support arrangement, the casing 60 is free to slide axially onthe radial keys 63, 83a, 63b, etc. relative to the casin 22. In order tolocate these two casingsaecurately relative to one another, an axiallyextending locating cylinder 33 is provided. This has at one end a flangewhich is bolted to the casing 60 (before casing 30 is inserted into theframe cylinder 22) by means of threaded fastening; 31. After the rotorend member, with the bearing casing 60 assembled thereto, is insertedinto casing 22, the other end flange of the locating cylinder 86 maybe-secured to the end flange 22a of the casing 22 by means of aplurality of suitable threaded fastenings, such as machine screws 88which are inserted from the open right-hand end of the flange 22a, theheads being recessed into the flange as shown in Fig. 3. It will beapparent that cylinder it prevents any longitudinal displacement of thebearing casing 60 relative to the outer frame casing 22.

* The end flange 22a of casing 22 is secured by means of a plurality ofthreaded fastenings 89 to the end flange [la or the main cylindricalframe member 21. At its right-hand end, main frame cylinder 21 carriesthe third journal bearing 28 by means of a plurality of threadedfastenings 90. Also carried by the right-hand end of cylinder 21 areradially inwardly extending walls forming a labyrinth seal 9| with theturbine rotor end portion 82. The mid-portion of seal 9| communicateswith an annular chamber 93 by means of a plurality of circumferentiallyspaced holes 94. As will be ap 'arent from Fig. 3, chamber 83communicates hrough a tube 95 with cooperating passages it in theleft-hand end flange of cylinder member 21, thence with the passage 69in casing 22.. Thus it will be apparent that the right-hand seal memberSi is also pressurized with air from the compressor.

- Turning now to Fig. 2, it will be seen that the first stagebucket-wheel, indicated generally at 91, has a hub portion formedintegral with a shaft extension 92, a first radially extending webportion to which is welded a circumferential rim portion, which in turncarries a circumferential row of buckets. This composite wheel structureis more fully described in United States Patent Number- 2,432,315,issued December 9, 1947 in the name of Alan Howard and assigned to thesame assignee as the present application.

it is provided with a coupling flange I to which is bolted an internallysplined coupling member IN. The input shaft I02 of a suitable loaddevice (not shown) extends through the bearing end cap 54 and isprovided with splines I09 engaging the cooperating splines of thecoupling member IOI.

As will be seen in Fig. 2, the bucket-wheels 91, 98 define a-cylindricalrabbet with each other, whereby they are maintained in proper coaxialrelation and are secured together by means of a circumferential row ofstuds I04 projecting through cooperating flanges formed integral withthe bucket-wheels. l

\ Projecting through a central axial bore in both bucket-wheels is astud I 05 which engages and is held concentric with the bore by means ofa plurality of axially spaced circumferential lands I06. At theright-hand or exterior end'of the turbine rotor, the stud I05 isprovided with an end head I01 which is secured to the adjacent face ofturbine rotor end portion 99 in the following manner. The head portionI0! is provided with two diammetrically opposite slots in which arelocated the two halves of a split washer I08. This washer is dividedalong a diameter, as shown in Fig. 5, so that the two halves can beasseinbled in a radial direction into the cooperating slots in the headI01. After being thus assembled, the split washer is secured by suitablethreaded fastenings I09 to the adjacent end face of the rotor endportion 99, with a shim or shims, of suitable thickness interposedbetween, as indicated at H0 in Fig. 2. By proper selection of thethickness of shim H0, the whole turbine rotor including bucket-wheels91, 98 and the end 10 by suitable threaded axially from the outercircumference of member H3 is a cylindrical portion II9 which has bothinternal splines engaging cooperating splines at II9 of the extreme endof rotor portion 92, and

, I22 with a coupling flange I23, the latter secured bybolts I24 to acoupling flange I25 formed in-,

tegral with the extreme end of compressor rotor, end member 59. Thearrangement of the splines of the torque-tube I2I permits it to float"freely in-an axial direction; therefore, means are provided forpositively locating it axially.- This may be in the form of a threadedpin'member I26 secured in the torque-tube I2I and having an portions 92,99 may be located axially a desired on the stud I05. This adjustment isrequired in order to permit proper selection of the clearance of thebucket-wheels with the associated stationary casing parts such as thenozzles which supply hot motive fluid to the buckets.

Attention is particularly directed to the fact that this importantadjustment can be made from the exterior of the turbine by simplyremoving the bearing end cap 54, unfastening the coupling member IOI andsliding it to the right on the output shaft I02. Thus the criticalnozzle-to-bucket clearances can be adjusted from the exterior of thepowerplant with substantially no disassembly thereof. -It will also beobserved that the engagement of the split washer I08 with the slottedhead I 01 prevents rotation of the stud I05 relative to the turbinerotor after assembly.

Referring new again to Fig. 3, it will be seen that the left-hand orinterior end of the stud I05 is provided with an end land III and athreaded portion II2. This threaded end portion engages the threadedbore of the coupling member II3, which serves a number of purposes. Thecentral portion of member H3 forms a spherical socket for one ball endof a thrust link II4. Ball member I I5 is held in the socket of memberII3 by means of a retaining ring 6 secured unthreaded cylindrical endportion I21 projecting into a recess in the outer circumferentialsurface of coupling member I I3. The left-hand end of thrust link H4 isprovided with a second ball member I28, which is received in a centralsocket in the coupling flange I25 and retained in position by means of aring I29 secured by threaded fastenings I30.

Thus it will be seen that torque is transmitted from the turbine rotortothe compressor rotor through the splined joints II9, I20,'I22, while thet o rotors are accurately positioned axially re ative to each'other bythe rigid thrust link I I4, which has auniversal ball-and-socketconnection with the respective rotors. This arrangement compensates forcertain misalignment which may arise betweenthe compressor and turbinerotors in initial assembly or may be causedvby certain deflections inthe powerplant casing due to exceptional stresses placed on the frameduring operation on a comparatively flexible foundation such as theframe of a locomotive. By this provision of a thrust link for locatingthe rotors relative to each other, and for taking any net thrust whichmay occur on either the compressor or turbine rotor, it is possible touse only a single thrust-bearing, that indicated at 25, as compared withprior art arrangements in which a separate thrust bearing would berequired for each rotor. By thus eliminating one thrust bearing, a veryappreciable saving in hearing friction power losses is effected. Costand complexity is, of course, likewise reduced by the elimination of theextra thrust bearing with its related lubricating and sealingarrangements.

In order to reduce the power losses due to windage, the torque-tube I2Iand its associated coupling members are surrounded by stationary shieldsfabricated of sheet metal. These include a first shield I3I surroundingthe coupling member I25, I23'and secured by a plurality of screwsfastening I I1. Extending I a ll expansion of the rotor will take placeboth to the right and to the left relative to the thrust hearing; and atthe'same time the thrust bearing assembly will not be subjected totemperatures as hi h as would be the case if it were located closer tothe discharge end of the combustion system and the very hot turbinenozzles and bucketwheels. The special torque-tube and thrust linkarrangement for connecting the turbine and compressor rotors providesfor a certain degree. of mis-alignment between the rotors, whilepermitting the turbine rotor to be adjusted axially relative to thecompressor so as to provide desired clearances between bucket-wheels andthe stationary casing portions. The special arrangement for eifectingthis adjustment from the exterior end of the powerplant withoutsubstantial disassembly thereof is particularly important from thestandpoint of ease of maintenance.

While a single embodiment of the invention has been described in detailherein, it will be obvious to those skilled in the art that many changesand substitutions of equivalents might be made; and it is desired tocover by the appended claim all such modifications as fall within thetrue spirit and scope of the invention.

Whatwe claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a turbine powerpiant, the combination of a frame with first,second, third, and fourth axially spaced radial bearing means and asingle thrust bearing means located intermediate said second and thirdradial bearings, a rotor assembly comprising a compressor rotor ofsubstantial axial length, one end of said compressor rotor having afirst axially extending portion supported in the first bearing, theother end of said rotor having a second axially extending portionsupported in the second bearing with thrust surf-aces cooperating withthe thrust bearing means and a first coupling flange member at theextreme end thereof located between the thrust bearing and the thirdradial bearing, a turbine rotor having a third axially extending portionsupported in and projecting through the third bearing toward said firstcoupling member, the turbine rotor having also a fourth axiallyprojecting portion at the opposite end thereof and adapted to besupported in the fourth bearing means, a thrust link with one endportion flexibly connected to said first coupling flange member, a studslidably projecting through a central bore in the turbine rotor andhaving a second coupling flange member flexibly connected to the otherend of the thrust link, said stud extending entirely through the turbinerotor and having at the exterior end thereof a radially extending flangemember with a surface parallel to an adja-- cent end surface of thefourth rotor portion, shim means interposed between said parallelsurfaces whereby the turbine rotor may be accurately positioned axiallyon the stud by insertion of a shim of suitable thickness, a torque tubemember surrounding the thrust link and having at one end a splinedconnection with the first coupling flange a member and at the other enda second splined 2. In an elastic fluid turbine, the combination of aframe with first and second axially spaced radial bearings and a thrustbearing axially spaced from one of the radial bearings, a rotor assemblycomprising a rotor member having a first axially extending end portionsupported in the first bearing'and projecting therethrough toward thethrust bearing, the other end of the rotor having a second axiallyextending portion supported in the second bearing and having an extremeend portion at the exterior side of the second bearing remote from thefirst bearing and defining a surface lying in a plane normal to the axisof the rotor, said rotor having limited axial sliding movement in saidradial bearings, a rotor locating stud arranged in a central boreextending entirely through the rotor. a first coupling member carried bythe extreme end of the rotor stud at the exterior side of the firsthearing remote from the second bearing, means connected to said firstcoupling member to locate the rotor stud axially relative to the thrustbearing, and a member carried by said rotor locating stud at theexterior side of the second bearing and having a radially extendingsurface parallel to said normal end surface of the second rotor portion,and shim means interposed in abutting relation between saidlast-mentioned member and said normal end surface of the second rotorend portion whereby the rotor may be accurately located axially relativeto the stud by insertion of a shim of suitable thickness.

3. In an elastic fluid turbine. the combination of a frame with firstand second axially spaced radial bearings and thrust bearing meansaxially spaced from one of the radial bearings, a rotor having at therespective ends thereof first and second axially extending portionsprojecting through and supported in said first and second radialbearings respectively, said rotor having a central axial bore extendingentirely therethrough, a rotor locating stud slidably disposed in therotor bore and projecting from each end thereof, means connected to oneprojecting end of the locating stud for positioning it axially relativeto the thrust bearing means, the other projecting end of the stud havinga radially extending portion adjacent the exterior end of the secondrotor end portion remote from the first bearing, and means associatedwith said last-mentioned stud and rotor end portions for adjusting therotor axially relative to the stud whereby the rotor may be accuratelypositioned axially in said radial bearings relative to the thrustbearing and frame.

4. In a turbine powerplant, the combination of a frame with first,second, third, and fourth axially spaced radial bearing means and asingle thrust bearing adjacent the second radial hearing, a, rotorassembly including a compressor rotor of substantial axial length, oneend of said rotor having a first axially extending portion supported inthe first radial bearing, the other end of said rotor defining a secondaxially extending portion supported in the second radial bearing, saidrotor also having portions with radially disposed thrust surfacescooperating with the thrustbearing means and a first flanged couplingmember at one extreme end of the compressor rotor located between thethrust bearing and the third radial bearing, a turbine rotor having athird axially extending portion supported in and projecting through thethird bearing towards said first coupling member, the turbine rotorhaving also a fourth axial projection at the opposite end thereof andsupported in the fourth bearing, a thrust link having two ends disposedbetween the adjacent ends of the compressor and turbine rotors andhaving a self-aligning connection at one of its ends with said firstcoupling flange member, a stud slidably projecting entirely through acentral bore in the turbine rotor and having a second coupling flangemember secured by a self-aligning connector to the other end of thethrust link whereby the studis positioned axially relative to the thrustbearing, said stud having at the exterior end of the turbine rotorremote from the compressor rotor a radially extending flange member witha surf-ace parallel to an adjacent end surface of said fourth rotorportion, shim means interposed in abutting relation between saidparallel surfaces whereby the turbine rotor may be accurately positionedaxially on the stud by insertion of a shim of suitable thickness, atorque tube member surrounding the thrust link and having at one end asplined con- 5. In a turbine powerplant, the combination.

of a frame with first, second, third, and fourth axially spaced radialbearings with a single thrust bearing means located adjacent said secondhear.- ing, the combination of a rotor assembly including a compressorrotor of substantial axial length with a first axially extending portionsupported I in the first bearing and a second axially extending portionsupported in the second bearing, the compressor rotor having also amember forming thrust surfaces cooperating with the thrust bearing meansand a first coupling fiange member at the extreme end of the compressorrotor adjacent of the thrust link, said stud having an end portionprojecting from the exterior end of the turbine rotor, and adjustingmeans connected to said exterior stud end portion for shifting theturbine rotor axially on the locating stud to alter the turbine rotorclearances, a coaxial torque tube member surrounding the thrust link andhaving at one end thereof a splined connection with said first couplingflange member and at the other end a second splined connectionwith saidsecond coupling flange member, the turbine rotor end portion projectingthrough the third bearing having a third splined connection with saidsecond coupling flange member, said third splined connection beingadapted to effect said axial adjustment of the turbine rotor on saidlocating stud.

6. In an elastic fiuid turbine, the combination a of a frame with firstand second axially spaced the third radial bearing, a turbine rotorhaving radial bearings and a thrust bearing axially spaced from one ofthe radial bearings, a rotor assembly including a turbine rotor memberhaving first and second axially extending end portions supported in saidfirst and second bearings respectively, said rotor having limited axialsliding movement in said bearings, a rotor locating stud disposed in acentral bore and extending entirely through the turbine rotor, a firstcoupling member carried by the extreme end of the rotor stud at theexterior side of the first hearing remote from the second bearing,locating means flexibly connected to said first coupling member toposition the rotor stud axially relative to the thrust bearing means,the rotor locating stud having a second end portion projecting from theturbine rotor at the side remote from the first coupling member, andmeans connected to said second stud end portion for adjustablypositioning the turbine rotor on the locating stud whereby the rotor maybe positively located relative to the thrust hearing from the exteriorend of the turbine and without substantial disassembly thereof.

BRUCE O. BUCKLAND. CHESTER S. RICE.

2,550,580 McLeod et al. Apr. 24, 1951

